Effects of forebrain ablations on avoidance learning in chicks

Abstract

The involvement of several regions of the newly-hatched chick's forebrain in mediating a learned avoidance response was investigated. Ablations of the posterolateral portion of the telencephalon resulted in complete loss of retention and relearning of the task. Dorsomedial ablations that included parts of the hyperstriatal complex caused a deficit in new learning but not in the retention of a presurgically acquired experience. In contrast, frontal ablations impaired retention and relearning of a preoperatively learned response but did not affect acquisition in chicks initially trained after surgery. These and other findings suggest that telencephalic structures in birds and mammals presumed to share a common phylogenetic ancestry may play analogous roles in the behavior of the two classes.